Int 83 Fn 0C  - Jm Pro Tracker V5.0 - ???                                  [s]

   AH = 0Ch
   DX bit 5 = ???
   ???

Return: CF clear if successful
       BX = ??? (FFFFh)
       CX = ??? (0000h)
       DX = ???
   CF set on error
       AX = error code (see #3647)